Scurvy is due to a deficiency in vitamin C that results in weak connective tissue and abnormally fragile capillaries that rupture easily, causing bleeding, anemia, edema, jaundice, heart failure, and death. Scurvy was a huge problem in sailors several centuries ago, because of the chronic lack of fresh fruit and vegetables during long sea voyages. James Lind, a Scottish naval surgeon, suspected that citrus fruits could prevent it based on some anecdotal observations. In 1754 Lind conducted what may be the world's first controlled clinical trial on 12 sailors with scurvy.
Lind divided the 12 sailors into pairs, and each group received a different treatment (sea water, various other concoctions, and lemons and oranges. The two who received lemons and organs were cured, but the others were not. Lind concluded that his hypothesis was correct, reported his findings, and recommended that sailors receive a ration of lime or lemon juice.
Unfortunately, 50 years passed before the British navy acted on Lind's recommendations and began to provide lime juice to sailors at sea. (This led to the nickname "Limeys" for British sailors.) It is also noteworthy that Lind was able to correctly identify a means of preventing scurvy even though he misunderstood the cause. He believed toxins within the body were normally released through pores in the skin and that scurvy was the result of damp sea air causing pores to close, thus trapping toxins within the body.